How can we find a number divisible by 7?

Throughtout my years of teaching experience, students love to find a shortcut or more faster way of finding the answer or a solution. When it came to using the divisiblity rules when finding the multiples of extreme larger numbers, all rules were easier than others with the exception of the number 7. The number 7 involves alot more steps that might seem more attracting and less appealing to the other rules.

Dividing by 7 (2 Tests)

• FIRST TEST
  Take the last digit in a number.
  Double and subtract the last digit in your number from the rest of the digits.
  Repeat the process for larger numbers.
  Example: 357 (Double the 7 to get 14. Subtract 14 from 35 to get 21 which is divisible by 7 and we can now say that 357 is divisible by 7.

• NEXT TEST
  Take the number and multiply each digit beginning on the right hand side (ones) by 1, 3, 2, 6, 4, 5. Repeat this sequence as necessary
  Add the products.
  If the sum is divisible by 7 - so is your number.
  Example: Is 2016 divisible by 7?
  6(1) + 1(3) + 0(2) + 2(6) = 21
  21 is divisible by 7 and we can now say that 2016 is also divisible by 7.